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Biodegradable polymeric matrix for long‐acting and zero‐order release drug delivery systems
Author(s) -
Li YouXin,
Feng XinDe
Publication year - 1990
Publication title -
makromolekulare chemie. macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 0258-0322
DOI - 10.1002/masy.19900330122
Subject(s) - polycaprolactone , copolymer , zero order , kinetics , biodegradable polymer , chemistry , drug delivery , matrix (chemical analysis) , controlled release , chemical engineering , materials science , polymer , first order , chromatography , nanotechnology , organic chemistry , mathematics , physics , quantum mechanics , engineering
Three types of biodegradable triblock copolymers, ABA, ABC and ACB, where A is polycaprolactone (PCL), B is polylactide (PLA) and C is polyglycolide (PGA), were used as matrix to test their controlled release behavior of Levo‐Norgestrel in the form of microsphere. It was verified that the overall release kinetics changes from in vitro first order to zero order when the percentage of PCL segments in all of the block copolymers decreases from 85 % to 60 −65 % with a long‐acting release time of 5 months or more. It is ascribed to the two release mechanisms, the diffusion release, contributed by the PCL segment, and the erosion‐caused release by PLA or PGA segment. At a certain ratio of segments the two release ways make a compromise to a constant rate of release, i. e. a zero‐order kinetics in these multiphase block copolymers.